An inductor coil is made with winding turns in a conical shape, tapered from a very small diameter and gradually increasing. Between the upstream-side cone and the outer shell, an inflow channel is formed. Due to exposure to the ion implantation beam, at least a portion of the resist is converted by exposure to the ion beam to contain an inorganic carbonized material. The release mechanism includes a lock-pin that is slidably disposed through the upright and is biased in a first position by a spring member disposed within the upright.